Electrical apparatus



Dec. 18, 1934. c. l. Mcm-:1L

I ELECTRICAL APPARATUS Original Filed Sept. 13. 1950 7 #am fr Y mf 7/Mio Thal Patented Dec. 18, 1934 UNITED STATES PATENT oFFl'cE ELECTRICAL APPARATUS Original application September 13, 1930, Serial No. 481,755. .Dividedl and this application August 20, 1931, Serial No. 558,373

4 Claims.

The present application is a division of my pending application, Serial No. 481,755, led September 13, 1930 and the invention embodied herein relates to electrical apparatus for use in charging systems of a type disclosed'in said pending application and more particularly to a novel 1 safety switch adapted for use in charging circuits wherein a reverse current relay or cut-out is employed to open a generator circuit when the I voltage of the generator becomes less than that of the battery to prevent discharging of the latter.

' It has been found in practice that the reverse current relay or cut-out employed in systems of the above type does not always function in the intended manner, due to the fact that the apparatus is occasionally subjected to a severe jolt, as for example when employed on an aircraft and at the instant of landing, which causes the armature of the reverse current relay to close accidentally, thereby allowing a heavy current to pass through the series coil of the relay, resulting in the armature being held closed by the flux produced by said current which flows from the battery through said series coil after the generaator voltage has fallen below that of the battery due to the generator speed decreasing under these conditions. l

Therefore, onev of the objects oi the present invention is to provide novel means whereby the above'and other diiiculties are overcome and the reverse current relay is made to function 'in the intended manner.

Another object is to provide a novel switch adapted to be employed in a charging circuit which includes a reverse current relay or cut-out, said switch embodying a multi-coil electro-magnet, the various coils of which are so formed and combined as to insure proper operationof the switch regardless of the electrical condition of the relay.

A further object is to provide a novel switch for controlling a reverse current relay or cut-out and embodying an electro-magnet provided with.

a plurality of coils whereby the contacts of the relay, if closed accidentally, are prevented from remaining closed.

Another object is to provide a novel switch for controlling a charging circuit which includes a reverse current relay whereby the charging eircuit may be automatically opened when the generator voltage falls below the battery voltage tol prevent battery current from flowing through the relay if the latter be closed accidentally,

(Cl. 20o-87) thereby .preventing said relay from remaining closed.

Another object is to provide novel means whereby a charging circuit is automatically opened when the generator voltage drops below that of the battery being charged and caused to remain open. l

A further object is to provide a novel switch for controlling a charging circuit for motor vehicles, said switch being so arranged that the charging circuit is initially closed by hand and thereafter opened automatically when the generator Voltage falls below the battery voltage and caused 4to remain open until manually reclosed.

A still further obj ect is to provide a novel switch for controlling a charging circuit whereby the latter is opened automatically when the generator voltage falls below the battery voltage and thereafter prevented from accidental closure and whereby said circuit may be manually closed and opened at the will of the operator.

Still another object is to provide a novel and improved automatic safety switch adapted for use in charging circuits on motor vehicles such as airplanes and automobiles.

The above and other objects and advantages of the invention will appear more 4fully hereinafter from consideration `of the detailed description which follows, together with the accompanying drawing, wherein is illustrated one embodiment of the invention. It is to be expressly understood, however, that the 'drawing is for the purpose of description-only, and is not designed as a denition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a schematic circuitarrangement which includes, among other elements, switch mechanism embodying the present invention;

Fig. 2 is a front elevation, partially in section, with parts broken away, of one form of switch adapted to be employed in accordance with the invention; and

Fig. 3 is a partially sectional side View thereof taken on line 3-3 of Fig. 2.

Referring now to Fig; 1, the embodiment of the invention illustrated therein is employed in a circuit including a direct-current generator provided with the usual voltage regulator and a reverse current relay or cut-out adapted to function in the usual manner in charging a storage battery,lsuch as is generally employedA for providing electrical energy for starting and lighting of a motor vehicle and for operating other auxiliary apparatus as is generally provided on such vehicles. 1 l

In the form shown, the voltage regulator comprises the usual solenoid 4 provided with ashunt or voltage winding 5 in series with a protective resistance 6, said solenoid being adapted upon energiz'ation of the coil 5 to open contacts 7 and 8, which are normally held closed by a spring 9,

thereby placing a resistance in series with the Ashunt eld winding 11 of the generator 12. The tension of the spring' 9 is adjusted so that upon the rise, of the voltage from the generator 12 above a predeterminedvalue, the contacts 7 and 8 are opened, thereby' causing resistance 10 to decrease the current flow in eld winding` 11, thus reducing the speed of the generator and decreasing the voltage thereof.

The reverse current relay or cut-out, which is provided for preventing the battery from discharging when the generator voltage drops below the battery voltage due to a decrease in generator speed or for any other reason,l comprises the usual solenoid I3 provided with a series winding 14 and shunt winding 15. A protective resistance 16 is placed in series with the shunt winding 15. Windings 14 and 15 are wound in such a manner that whencurrent flows therethrough from the generator their fiux is cumulative, thereby holding the contacts 17 and 18 closed against the tension of spring 19, but when the current flows from the battery to the generator due to the voltage of the latter being greater than that ofthe generator, the magneto-motive forces of the coils oppose each other, thereby causing the contacts 17 and 18 to be opened by the spring 19. As is understood in the art, coil 15 functions to initially close the contacts 17 and 18, whereby current is then caused to ow through coil 14, thus aiding the coil in keeping said contacts closed.

As pointed out hereinbefore, it has been found in practice that a reverse current relay or cutout does not always function in the intended manthe battery, thus preventing any battery current from flowing through the series coil of the reverse current relay if the latter be closed accidentally, which would tend to hold it closed and cause discharging of the battery andpossibly a burning out of the generator due to said battery current owing therethrough.

In the form shown, said means comprises an l electromagnet or solenoid including a core 20 and provided with a shunt winding 21 and a series winding 22 which correspond to windings 15 and 14, respectively, of the reverse current relay and are adapted tohold contacts 23 and 24 closed when the battery 25 is being charged by the generator andare wound in a manner similar to that of coils 15 and 14, so that when the generator voltage drops, current from the battery 25'owing through said coils is in opposite directions, thereby causing spring 26 to open the contacts 23 and 24 at-the same time that contacts 17 and 18 are opened by spring 19 and the action of ,coils 14 and 15. This device diifers from a reverse current relay in that the tension' of spring 26 is of such a value as to prevent 'the contacts 23 and 24 from closing only by attraction of the armature due to generator current passing through coil 21, and the contacts 23 and 24 must initially be closed manually against the tension of' said spring whereupon generator current flows through coil 22 andthe flux produced therein is of the same strength as that of coil 21, thereby causing the solenoid 20 to hold said contacts closed.

It will therefore be apparent that before the system can operate, contacts 23 and 24 must be closed manually, but when once closed they will be held closed by the combined action of coils `21 and 22. Due to the tension of the spring 26,

accidental closure of the' contacts cannot occur after they are opened, asmay happen in the case of the reverse current relay, in which the tension of the spring 19 is much lower and insufficient to prevent the contacts 17 and 18 coming 4 together when the vehicle on which the relay is carried is subjected to a jolt or` jar. Spring 19 must, of necessity, be made light in order that the relay function properly, because if the tension also be opened manually as well as automati` cally, if desired, at the will of the operator of the motor vehicle upon which said switch is "mounted, which will ,be pointed out more particularly in connection with Figs. 2 and 3.

The device is provided with three terminals 27,

28, and 2,9, the first two of which are adapted to be connected to the plus or positive side of the generator and the positive side of the battery, respectively, and the third to the negative side of the generator and the negative side of the battery.

l Referring now to Figs. 2 and 3, which show one form of mechanical embodiment of the invention, the device illustrated therein comprises a rectangular frame provided with integral anges 31 and 32 at one end thereof for securing the device to the instrument panel of an aircraft or the dashboard of an automobile. Threaded apertures 33 `are formed in the frame" forreceivingscrews 34 by means of which a pair of coverplates 35 .and 36 are secured to the frame. The core 20, on which are wound the coils 21 and 22, is carried by a rectangular member orv partition 37 which ispressed into the frame either from one side or the other thereof, and also carries an adjusting mechanism tobe described hereinafter. Terminals 27, 28, and 29A extend from and pass through the othex` end of the frame and are -in- 'sulated 'therefrom by means of bushings 38, 39,

and 40 of some suitable insulating material, such as fibre, bakelite, or the like. The inner ends of the terminals are provided withbinding posts 4l, 42, and 43, respectively, fon connectingthe coils 21 and 22 and contact 24 thereto.

The movable contact 23 is carried by an armature 44 positioned parallel with and longitudinally of the coils and is pivoted by means of a pin 45 passing therethrough and supported in the partition 37. Coil 22 maybe connected to armature 44 in any suitable manner, as by soldering `the end thereof to said armature as indicated at 44a. Fixed contact 24 is carried by a bracket 46 of some suitable conducting material, such as brass or copper, which is\rigidly secured to the terminal 28 by means of the screw of the binding post 42. When the coils 21 and 22 are energized, the magnetic path of the ux produced thereby is from the core 20 through the partition 37, the armature 44, and back to the core 20 through the portion 20a of the latter. It will be apparent that upon energization of the coils the armature 44 will be attracted to the left by the core 20 due to themagnetic gap which exists between member 20a and said armature when the contacts 23 and 24 are open, thereby closing the contacts against the tension of the spring 26, which is secured to one end of said armature.

Means are provided for adjusting the tension of the spring 26, and in the form shown comprise a threaded member 47 having a square end piece 48 formed integral therewith to which spring 26 is secured. Threaded member. 47 is carried by a bracket 48a provided with a threaded aperture through which the member 47 passes and by means of which said member is adapted to be moved either to the right to decrease the tension on the spring 26, or to the left to increase' the tension by rotating the head 49 of the member 47. Guide member 5o is secured to the shelf 37-by suitable means, such as a screw 51, and serves to guide the end piece 48 and also to support the latter. In order-to prevent any change in the adjustment, a ratchet wheel 52 is provided which is carried by the threaded member 47 concentrically therewith and is adapted to be engaged by a pawl 53, the latter being secured to the bracket 50 by means of screw 51. The teeth on the ratchet wheel are arranged to provide rotation thereof in either direction against the pressure of the pawl 53 but prevented from rotation by the latter until some external force is applied thereto, as by means of rotation of the head 49 of the threaded member 47. It will be apparent from this construction that once an adjustment is made it will be maintained until altered by manipulation of the threaded member 47.

Means are also provided for manually closing and opening the contacts 23 and 24 at the will of the operator, and in the form shown comprise a knob 54 secured to or made integral with a rod 55 which passes through an aperture formed in that portion of the frame 30 which is adapted to lie on the face of the instrument panel. The rod is provided witha set of collars or discs 56, 57 and 58 spaced apart from each other therealong. A leaf spring 59 is secured at its one end to the frame 30, as by means of a rivet 60, and has its free Vend interposed between the collars 56 and 57 whereby, upon inward and outward movement of the knob 54, the latter is returned to its normal position, as indicated in Fig. 2. 'Ihe collar 57 is positioned on the rod 55 so that when the contacts 23 and 24 are closed it bears against an angular projection 61 secured to the end yof the armature 44 opposite from that which carries the fixed contactl 23, whereby upon an inward push of knob 54 the contacts 23-24 may be opened. 'Ihe collar 58 is positioned on the end of the rod 55-so that upon an outward movement of the knob 54 it engages the projection 61 and causes the armature 44 to move on. its pivot pin to close the contacts 23 and 24.

The operation of the device is as follows: When the engine of the motor vehicle on which the device is mounted isstarted the generator 12 is rotated thereby and current from the latter ows through the shunt coil 15, causing enervgization of the reversecurrent relay to close the contacts 17 and 18. No current yflows through series coil 14 until contacts 23 and 24 are closed manually when it is desired to charge the battery 25. To close said contacts, knob 54 is pulled outward, causing current from the generator to pass through coils 21 and 22, thereby` producing a iiux which tends to hold said contacts in closed position. Contacts 17 and 18, being closed, cause current to flow through coil 14, thereby increasing the flux in the reverse current relay to maintain said contacts in closed position.

The novel switch of the invention functions in a manner similar to the reverse current relay except that it must be closed manually, while the relay closes automatically, but both are adapted to be opened automatically and simultaneously. Therefore, when the generator voltage drops below that of the battery, battery current will ow through coils 21 and 22 and coils 14 and 15 in opposite directions, thereby substantially CII decreasing the flux thereof, causing springs 26 and 19 to automatically open the contacts 23-24 and 14-15. f However, after the contacts 23-24 are openthey are held open by the spring 26, and cannot be closed again until the knob 54 is pulled outward to cause current from the generator to traverse the coils in the same direction and thereby hold the contacts closed.

If the operator desires to discontinue charging the battery at any time, he simply has to push the knob 54 inward `to break the contacts 23 and 24, which are thereafter held open by means of spring 26, as pointed out above. When the contacts 23 and 24 are opened, either manually or automatically, no battery current can flow through the series coil 14 of the reverse current relay should the contacts 17 and 18 be closed accidentally by a sudden jolt or jar imparted to the motor vehicle as, for example, when landing an airplane.

It will be seen from the foregoing description that there is provided a novel automatic safety switch adapted for -use particularly in aircraft, which is frequently subjected to jolts and jars, whereby accidental closing of the reverse cur-x rent relay is prevented, thus preventing discharg ing of the battery through the generator. The mechanical embodiment of the switch is simple in structure, thereby facilitating the assembly and manufacture thereof and reducing the cost of manufacture.

While only one form of the switch embodying the present invention is shown and described, various other changes in the mechanical form, arrangement and construction of parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention. Reference is therefore to be had to the appended claims for a definition of the limits of the invention. What is claimed is:

l. A reverse current switch comprising a substantially rectangular fra-me having a face plate at one end thereof forming flanges projecting on I two sides of the end of the frame for ,mounting the latter on a panel whereby said frame is adapted to project perpendicularly from the rear of thepanel, a shelf extending across theframe,

a solenoid having a core secured tothe shelf on one side thereof and within the boundaries of the frame, an amature pivoted on the shelf and operated by the solenoid and forming a closed magnetic path with the core and shelf when attracted by the solenoid, said armaturev projecting on both sides of the shelf parallel to the core,

shelf and operated bythe solenoid and forming a fixed contact carried by the frame, a movable contact carried by the armature at one end thereof, said contacts being in circuit with the solenoid by which theyl are held closed when actuated manually to closed position, resilient adjustable means carried on the other side of the shelf and connected to the other end of the armature for opening said contacts when the solenoid is de-energized, and a knob operatively connected to the latter end of the armature for moving said armature to open r close the contacts, said knob projecting through the face plate whereby the switch may be operated manually from the front of the panel.

2. A reverse current switch comprising a substantially rectangular frame having aface plate at one end thereof forming flanges projecting on two sides of the end of the frame for mounting the latter on a panel whereby said frame is adapted to project perpendicularly from the rear of the panel, a shelf extending across the frame, a solenoid having a core secured to the shelf on one side thereof and within the boundaries of the frame, an armature pivoted on the shelf and operated by the solenoid and forming a closed magnetic path with the core and shelf when attracted by the solenoid, said armature projecting on both sides of the shelf and parallel to the-core, a fixed contact carried by the frame,l

a movable contact carried by the 'armature at one end thereof, sai'd contacts being in circuit with the solenoid by which they are held closed when actuated manually to closed position, resilient adjustable means carried on the other side of the shelf and connected to the other end of the armature for opening said contacts when the solenoid is de-energized, a knob operatively connected to the latter end of the armature for moving said armature to open or close the contacts, said knob projecting through the face plate whereby the switch may be operated manually from the front of the panel, and terminals on said frame and insulated therefrom for connecting the switch to a battery andl generator.

3. A reverse current switch comprising a substantially rectangular frame having a face plate at one end thereof forming flanges projecting at two sides of the end of the frame for mounting the latter`;' on' a panel wherebyL said frame is adapted to project -perpendicularly from the rear of the panel, a shelf extending across the frame, a solenoid having a core secured to the shelf on one side thereof and within the boundaries of the frame, an armature pivoted on the a closed magnetic path with the core and shelf when attracted by the solenoid, said armature projecting on both sides of the .shelf and parallel to the core, a fixed contact carried by the frame, a movable contact carried by the armature at one end thereof, said contacts being in circuit with the solenoid, by which they are held closed when actuated manually to closed position, resilient adjustable means carried on the other side of the shelf and connected to the other end of the armature for opening s'aid contacts when the solenoid is de-energized, a knob operatively connected to the latter end of the armature for moving said armature to open or close the contacts, said knob projecting through the face plate whereby the switch may be operated manually from the front of the panel, and a second resilient means for returning the knob to inoperative position after the contacts have been operated thereby.

4. A reverse current switch comprising a substantially rectangular frame having a face plate at one end thereof forming anges projecting on two sides at the end of the frame for mounting f the latter on a panel whereby said frame is adapted to project perpendicularly from the rear of the panel, ashelf extending acrossthe frame, a solenoid having a core secured to the shelf on one side thereof and within the boundaries of the frame, an-armature pivoted on the shelf and operated by the solenoid and forming a. closed magneticv path with the coreand shelf when attracted by the solenoid, said armature projecting on both sides of the shelf and parallel to the core, a fixed contact carried by.the frame, a movable contact carried by the armature at one end thereof, said contacts being in circuit with the solenoid by which they are held closed when actuated manually `to closed position, resilient adjustable means 'carried on the other side of the shelf and connected to the other end of the armature for opening said contacts when the solenoid is de-energized, a knob operatively connected to the latter end of the armature for moving said armature to open or close said contacts, said knob projecting through vthe face plate whereby the switch may be operated manually from the front of the panel, a second rev ient means for returning the knob to inope tive position after the. contacts have been operated thereby, and`terminals on said frame and insulated therefrom for connecting the switch toa battery and generator.

CHARLES I. MCNEIL. 

